Using biochar to cover mining waste

Challenge the practice is addressing: The practice examines how biochar can be used to cover mining waste in projects in northern mining industry. By examining how the use of biochar affects the water economy, as well as carbon and nutrition balance of the multi-level coverage and the growth layer, the best ways to improve bio cover’s durability and stability are defined.

Concrete practice to achieve the expected goal: The project ran laboratory analyses as well as studies on a pilot site’s tailings pool to find out how biochar affects moraine cover structures. In addition, the affect of biochar on revegetation was experimented in a greenhouse environment. Bio-char produced from different materials (spruce, birch, construction wood, sewage sludge) were tested. According to the results, spruce-based biochar 1) increased the water-holding capacity, 2) raised the pH levels and reduced the amount of soluble metals in the substrate layer, and 3) reduced the amount of metals accumulating in plants. Furthermore, a survey was conducted on extractives industry experts in Finland and Sweden. As a result, it was found that there is a lack of information on the long-term effects and durability of bio covers. In addition, permitting processes are considered difficult.

Expected impact/goal of the practice: The project aims to find the best ways to improve bio covers currently used in northern mining industry. The objectives are especially to develop the durability and stability of the cover, prevent erosion, and improve the sustainability of water management, carbon balance and nutrient economy.

Who is the target user group of the practice/intervention or implementing the practice/intervention? The target group of the practice are researchers, engineers and industry representatives aiming to develop environmental rehabilitation practices and landscaping solutions in the field.